Seshiro the Anointed

Other Snake creatures you control get +2/+2.
Whenever a Snake you control deals combat damage to a player, you may draw a card.

Vitalizing Wind

Creatures you control get +7/+7 until end of turn.

Patron of the Orochi

Snake offering (You may cast this spell any time you could cast an instant by sacrificing a Snake and paying the difference in mana costs between this and the sacrificed Snake. Mana cost includes color.)
{T}: Untap all Forests and all green creatures. Activate only once each turn.

Shidako, Broodmistress

{G}, Sacrifice a creature: Target creature gets +3/+3 until end of turn.

Orochi Eggwatcher

{2}{G}, {T}: Create a 1/1 green Snake creature token. If you control ten or more creatures, flip Orochi Eggwatcher.

Orochi Eggwatcher // Shidako, Broodmistress

Tangle

Prevent all combat damage that would be dealt this turn.
Each attacking creature doesn't untap during its controller's next untap step.

Double Vision

Whenever you cast your first instant or sorcery spell each turn, copy that spell. You may choose new targets for the copy.

Nature's Will

Whenever one or more creatures you control deal combat damage to a player, tap all lands that player controls and untap all lands you control.

Prevent all combat damage that would be dealt this turn.

Sachi, Daughter of Seshiro

Other Snake creatures you control get +0/+1.
Shamans you control have "{T}: Add {G}{G}."

Tangle Asp

Whenever Tangle Asp blocks or becomes blocked by a creature, destroy that creature at end of combat.

Moss Viper

Sosuke's Summons

Create two 1/1 green Snake creature tokens.
Whenever a nontoken Snake you control enters, you may return Sosuke's Summons from your graveyard to your hand.

Might of the Masses

Target creature gets +1/+1 until end of turn for each creature you control.

Spidersilk Armor

Creatures you control get +0/+1 and have reach. (They can block creatures with flying.)

Hooded Hydra

Hooded Hydra enters with X +1/+1 counters on it.
When Hooded Hydra dies, create a 1/1 green Snake creature token for each +1/+1 counter on it.
Morph {3}{G}{G}
As Hooded Hydra is turned face up, put five +1/+1 counters on it.

Ambush Viper

Nemesis Mask

All creatures able to block equipped creature do so.
Equip {3} ({3}: Attach to target creature you control. Equip only as a sorcery. This card enters unattached and stays on the battlefield if the creature leaves.)

Orochi Hatchery

Orochi Hatchery enters with X charge counters on it.
{5}, {T}: Create a 1/1 green Snake creature token for each charge counter on Orochi Hatchery.

Orochi Sustainer

River Boa

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
{G}: Regenerate River Boa.

Mire Boa

Swampwalk (This creature can't be blocked as long as defending player controls a Swamp.)
{G}: Regenerate Mire Boa. (The next time this creature would be destroyed this turn, instead tap it, remove it from combat, and heal all damage on it.)

Naturalize

Venom

Enchant creature
Whenever enchanted creature blocks or becomes blocked by a non-Wall creature, destroy the other creature at end of combat.

Junkyo Bell

At the beginning of your upkeep, you may have target creature you control get +X/+X until end of turn, where X is the number of creatures you control. If you do, sacrifice that creature at the beginning of the next end step.

Forest

Sakura-Tribe Elder

Sacrifice Sakura-Tribe Elder: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Parallel Evolution

For each creature token on the battlefield, its controller creates a token that's a copy of that creature.
Flashback {4}{G}{G}{G} (You may cast this card from your graveyard for its flashback cost. Then exile it.)